For an emergency such as disaster, wireless communication systems provide services which promptly inform users of the emergency. For example, when a disaster occurs, a base station in the wireless communication system provides a service which broadcasts a message informing of the disaster over a specific frequency so that all of users can recognize the disaster.
In particular, since a catastrophe such as earthquake, fire, or terror attack can cut a line interconnecting the base station and a core network, a conventional wireless communication system provides a service for handling the isolation of the base station by periodically transmitting and receiving a keep-alive message between the base station and the core network.
However, when the base station and the core network periodically transmit and receive the keep-alive message over a certain number of times and the transmission and reception of the keep-alive message continuously fails over a threshold number of times, the using of the keep-alive message can detect the isolation of the base station. In result, it takes a long time to detect the isolation of the base station. For example, when the keep-alive message transmitted and received at intervals of 5 seconds continuously fails for 11 times, the conventional base station and core network determine the line disconnection between the base station and the core network and accordingly it takes 55 seconds to detect the isolation of the base station. Though 55 seconds can be a short time period in general situations, it is not short at all in case of an emergency could damage human life and property within a few seconds.
In this respect, a method and an apparatus for detecting the emergency of the base station within a short time and maintaining the communication of the mobile station in the base station are demanded.